This book is a sequel to Wittgenstein's Poker by David Edmonds and John Eidinow who vividly described the background and the events at the showdown between Wittgenstein and Popper at the meeting of the Cambridge Moral Sciences Club in 1946. On that occasion the two Viennese masterminds confronted each other in a brief exchange which ended when Wittgenstein left the room after (possibly) menacing Popper with a poker.

Peter Munz has unparalleled qualifications for this assignment because he is the only person who was a student with both Popper and Wittgenstein, moreover he is one of the few people still alive who witnessed the non-debate in 1946. Munz arrived in New Zealand with his family in 1940 as a German Jewish refugee. He attended Popper’s lectures when he started an MA in History at Canterbury University College, Christchurch and they struck up a lifelong friendship which survived better than most of Popper's relationships with his students and colleagues. Munz moved on to Cambridge for further postgraduate work in history and he pursued his interest in philosophy as a member of Wittgenstein's seminar. He spent the rest of his academic career in history at Victoria University in Wellington where he wrote more than a dozen books on history and several others developing and exploring the Darwinian aspects of Popper's theory of knowledge.

Munz has radically upgraded his estimate of Wittgenstein's contribution since 1986 when he published Our Knowledge of the Growth of Knowledge: Popper or Wittgenstein?. That book made a strong case for Popper against Wittgenstein, and also against Kuhn and Rorty. All three were depicted as agents of relativism, promoting the balkanisation of intellectual life into self-contained, autistic specialties. Munz now argues that Wittgenstein and Popper should have stood together as colleagues to pool their ideas and produce a doctrine with the strengths of each. However this was precluded by their unyielding resistance to rival schools of thought.

The organisation of the book is complicated by Munz's larger game plan to establish Darwinian evolutionary epistemology as the pre-eminent development in modern thought. The second part of the book is devoted to a critique of Evolutionary Psychology and this gives the appearance of two separate books in one, unless the larger project is kept in mind as the framework that pulls the two pieces together. According to this framework, scientific knowledge is an evolutionary product of human activity. Knowledge itself evolves in a dialectic fashion, propelled by human ingenuity, checked by various forms of criticism including experimental and other practical tests. Contrary to classical empiricism and rationalism, neither sensations nor intuitions have foundational status. Rationality does not consist of avoiding error or achieving certainty but instead means the willingness to take on board criticism with a view to improvement. Truth is not a terminus but a regulative principle.

Behind this framework stands the giant figure of Charles Darwin and also, more immediately, the almost forgotten shade of Karl Buhler. He was one of the really important pioneers of psychology and language in the twentieth century who, incidentally, taught both Wittgenstein and Popper (so far as anyone can claim to have taught Wittgenstein). He promoted a non-reductive psychology, insisting that human behaviour cannot be reduced to the causal chains of physics and behaviourism. Both Popper and Wittgenstein took this on board, though in different ways. Wittgenstein developed his views on "forms of life" and "language games" while Popper formulated his theories of critical rationalism and conjectural objective knowledge.

According to Munz, both missed a vital part of the picture. Popper refused to be distracted from the quest for truth by the problem of meaning which in consequence remained something of a mystery in his scheme. Wittgenstein for his part was obsessed with meaning and did not care about the growth of knowledge or the state of science and society. Munz suggests that Wittgenstein’s theory of meaning as a function of rule-following behaviour in relatively closed speech communities fills the gap in Popper's program. According to Munz that is the lesson that Popper should have learned from Wittgenstein, while the latter should have picked up from Popper the importance of critical appraisal of "forms of life" and their conventional rules in order to move from closed or tribal societies towards more open societies.

Munz re-wrote history in the form of an imaginary dialogue between Popper and Wittgenstein (at the Moral Sciences Club circa 1946) to show how they might have worked through some of their differences and misunderstandings to reach a happy if grudging accommodation. Munz concluded his revised history with a flourish: "Everyone started laughing and the room was filled with a fine sense of convivial agreement". If only! That marks the end of the first part of the book. The case that Munz has provided for a creative synthesis is challenging and instructive, though not entirely convincing. The weakness of Popper on meaning is asserted without a convincing explanation and it remains to be seen whether the cohorts of the two champions will come to the party (with a fine sense of convivial agreement!) and find illumination from a source that they have previously regarded with disdain.

The second part of the book takes up some of the difficulties which need to be resolved to provide a convincing explanation for the miracle of knowledge and its growth, without recourse to the simple certainties of positivism and the mirror theory of scientific knowledge. Here Munz brings a great deal of criticism to bear upon some American scholars who are making careers out of evolutionary psychology without, on his account, taking on board the full Darwinian account of the evolutionary process. This part of the book does not really mesh smoothly with the first and the technical level of the argument is likely to strain the general reader. Munz writes clearly but the argument is dense.

Throughout the book a great deal of scholarship is on display, fortunately enlivened in the first part by some interesting and even-handed commentary on the personalities and eccentricities of the two arch rivals.